Electronic mail (“e-mail”) messages may be encoded using one of a number of known protocols. Some of these protocols, such as Secure Multiple Internet Mail Extensions (“S/MIME”) for example, rely on public and private encryption keys to provide confidentiality and integrity, and on a Public Key Infrastructure (PKI) to communicate information that provides authentication and authorization. Data encoded using a private key of a private key/public key pair can only be decoded using the corresponding public key of the pair, and data encoded using a public key of a private key/public key pair can only be decoded using the corresponding private key of the pair. The authenticity of public keys used in the encoding of messages may be validated using certificates. In particular, if a user of a computing device wishes to encrypt a message before the message is sent to a particular individual, the user will require a certificate for that individual. That certificate will typically comprise the public key of the individual, as well as other identification-related information. Similarly, if a user of a computing device receives a message that has been digitally signed by a particular individual, the user will require the proper certificate (comprising a public key) for that individual if the user wishes to verify the digital signature in the message.
Typically, in known e-mail applications, if an attempt is made to employ a particular certificate to, for example, encrypt a message that the user intends to send to an individual, and that certificate contains an e-mail address, but the e-mail address contained in that certificate does not match the e-mail address to which the message is to be sent, an error message indicating an address mismatch would normally be returned to the user. As a result of the address mismatch, the message would be neither encrypted nor sent.